Which relation is a function? {(1, 4), (2, 3), (3, 2), (4, 1)}

{(4, 2), (3, 3), (2, 4), (3, 2)}

{(1, −1), (−2, 2), (−1, 2), (1, −2)}

{(1, 2), (2, 3), (3, 2), (2, 1)}

A relation from a set X to a set Y is called a function if each element of X is related to exactly one element in Y. That is, given an element x in X, there is only one element in Y that x is related to.

Step-by-step explanation:

A relation from a set X to a set Y is called a function if each element of X is related to exactly one element in Y. That is, given an element x in X, there is only one element in Y that x is related to.

1 and 0

step-by-step explanation: